If you’re still confused about holiday hours or a random Tuesday in late September, just call the store directly. The number is on the M&S website, and the staff are surprisingly cheerful for people who spend their days folding pants.
Or, you know, check Google Maps. It’s usually updated, but take it with a grain of salt. Sometimes Google thinks the store opens at 8 AM, and it’s wrong. Very wrong. Trust me, nobody wants to be that person staring at a “Closed” sign while a bird laughs at you.